linux-kernel - Re: [PATCH] ALSA: firewire-motu: fix buffer overflow in hwdep read for DSP events

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Message-ID: <87qzt9vw9l.wl-tiwai@suse.de>
Date: Fri, 05 Dec 2025 15:27:50 +0100
From: Takashi Iwai <tiwai@...e.de>
To: Junrui Luo <moonafterrain@...look.com>
Cc: Clemens Ladisch <clemens@...isch.de>,
	Takashi Sakamoto <o-takashi@...amocchi.jp>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Takashi Iwai <tiwai@...e.de>,
	linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yuhao Jiang <danisjiang@...il.com>
Subject: Re: [PATCH] ALSA: firewire-motu: fix buffer overflow in hwdep read for DSP events

On Wed, 03 Dec 2025 05:27:03 +0100,
Junrui Luo wrote:
> 
> The DSP event handling code in hwdep_read() could write more bytes to
> the user buffer than requested, when a user provides a buffer smaller
> than the event header size (8 bytes).
> 
> Fix by using min_t() to clamp the copy size, This ensures we never copy
> more than the user requested.
> 
> Reported-by: Yuhao Jiang <danisjiang@...il.com>
> Reported-by: Junrui Luo <moonafterrain@...look.com>
> Fixes: 634ec0b2906e ("ALSA: firewire-motu: notify event for parameter change in register DSP model")
> Signed-off-by: Junrui Luo <moonafterrain@...look.com>

Applied now.  Thanks.

BTW, the code there has another bug; the loop of put_user() above your
change doesn't check whether it has an enough remaining size.  When
count isn't aligned with 4 bytes, it might cause a similar overwrite.
It has to be corrected, too.


Takashi